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Previous issue date: 2012-09-14 / There are a number of damaging mechanisms that various materials can suffer in service.
However, when working with polymer composite materials, this is something that requires
analysis, especially when exposed to adverse environmental conditions. Thus, the objective
of the present thesis is the study of the direct influence of environmental aging and the
form of hybridization of the reinforcement woven on the structural stability,
surfacedegradation and fracture process of polymer composites laminates. For this, the
development of two polymer composite laminates was necessary, where one of them was
reinforced with a bi-directional woven with hybrid strandsofkevlar-49/glass-Efibers, and
the other also with a bi-directionalwoven, however with weft and warpformed of
alternating strandsof Kevlar-49 fibers and glass-E fiber The reinforcementwoven are
industrially manufactured. Both laminates use a polyester resin as a matrixand are made up
of four layers each. All laminates were industrially prepared by the hand lay-up method of
manufacturing. To do this, test specimens were manufactured of the respective laminates
and submitted to environmental aging accelerated through the aging chamber. They were
exposed to alternating cycles of UV radiation and moisture (heated steam) for a standard
defined period. At the end of the exposure period the specimens were subjected to
mechanical tests of uniaxial tensile and bending in three points and to the
characterizationsof the fracture and surface deterioration. In addition, they were submitted
to a structural degradation assessment by the measurement of mass variation technique
(MMVT) and the measurement of thickness variation technique (MTVT), this last
technique being developed in this thesis. At the end of the analysis it was observed that the
form of hybridization of the reinforcement woven and the aging process directly influence
with losses or gain in mechanical properties, with losses in the structural degradation and
in the formation and propagation of damage mechanism of the developedcomposite
laminates / S?o v?rios os mecanismos de danos que os diversos materiais podem sofrer em servi?o. No
entanto, ao se trabalhar com os materiais comp?sitos polim?ricos isso ? algo que necessita
de an?lises principalmente quando expostos a condi??es ambientais adversas. Logo, a
respectiva tese objetiva o estudo da influ?ncia direta do envelhecimento ambiental e da
forma de hibridiza??o dos tecidos de refor?o no comportamento mec?nico, degrada??o
estrutural (dimensional e de massa) de laminados comp?sitos polim?ricos. Para tanto se fez
necess?rio o desenvolvimento de dois laminados comp?sitos polim?ricos, onde um deles ?
refor?ado com um tecido bidirecional com mecha h?brida de fibras de kevlar-49/vidro-E e
o outro com um tecido tamb?m bidirecional, por?m com trama e urdume formadas com
mechas alternadas de fibras kevlar-49 e fibras de vidro-E. Os tecidos de refor?o s?o de
fabrica??o industrial. Ambos os laminados utilizam como matriz a resina de poli?ster,
sendo constitu?dos de quatro camadas cada. Todos os laminados foram confeccionados
industrialmente pelo m?todo de fabrica??o handlay-up. Desta forma, foram fabricados
corpos de provas (CP s) dos respectivos laminados e submetidos ao envelhecimento
ambiental acelerado atrav?s da c?mara de envelhecimento. Os mesmos foram expostos aos
ciclos alternados de radia??o UV e umidade (vapor aquecido) por um per?odo definido em
norma. Ao t?rmino do per?odo de exposi??o os CP s foram submetidos aos ensaios
mec?nicos de tra??o uniaxial e flex?o em tr?s pontos e ?s caracteriza??es da fratura e da
deteriora??o superficial. Al?m disso, foram submetidos ? avalia??o da degrada??o
estrutural mediante a t?cnica de media??o de varia??o de massa (TMVM) e a t?cnica de
medi??o de varia??o de espessura (TMVE), sendo essa ?ltima desenvolvida nesta tese. Ao
t?rmino das an?lises foi observado que a forma de hibridiza??o dos tecidos de refor?o e o
processo de envelhecimento influenciam diretamente, seja com perdas ou ganho
naspropriedades mec?nicas, com perdas na degrada??o estrutural e na forma??o e
propaga??o do mecanismo de dano dos laminados comp?sitos desenvolvidos
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/15592 |
| Date | 14 September 2012 |
| Creators | Felipe, Renata Carla Tavares Santos |
| Contributors | CPF:16080564491, http://lattes.cnpq.br/1196595599227394, Freire J?nior, Raimundo Carlos Silv?rio, CPF:02306444498, http://lattes.cnpq.br/1042806990155996, Silva, Luiz Claudio Ferreira da, CPF:79098630472, http://lattes.cnpq.br/3812459994118013, Silva, Rosana Vilarim da, CPF:75225760406, http://lattes.cnpq.br/6661189556213632, Amorim J?nior, Wanderley Ferreira de, CPF:87244152434, http://lattes.cnpq.br/8131607733881361, Aquino, Eve Maria Freire de |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Engenharia Mec?nica, UFRN, BR, Tecnologia de Materiais; Projetos Mec?nicos; Termoci?ncias |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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